Fiber optic splice closure

ABSTRACT

A splice closure including a frame having a partition wall to define front and rear access areas for the closure. The frame carries one or more splice trays on a first surface portion making the splices accessible from the front or first access area. A slack storage compartment is provided on the second surface portion. The slack storage compartment includes one or more pairs of opposing sidewalls that define an access opening for the slack that is accessible from the rear access area. An extension member for the frame is disclosed for obtaining greater amounts of slack from the cable, such as for a taut sheath cable splice. A tandem longitudinal arrangement of splice trays is also disclosed and may be used for a taut sheath ring splice or for repairing a severed cable.

FIELD OF THE INVENTION

The invention relates to the field of fiber optic communications systemsand equipment and, more particularly, to a splice closure for thestorage and protection of fiber optic splices and associated slack.

BACKGROUND OF THE INVENTION

Optical fiber communications systems are used extensively in thetelecommunications industry due to their large information carryingcapacity, their virtually noise-free performance, and the long spandistances achievable with optical fibers before regeneration andamplification of the signal are required. Practical limits on thelengths of optical fiber cables that can be manufactured and installedtypically require that several splice points be included over the totalcable route.

At each such splice location, all of the optical fibers are separatedfrom the other protective cable components for splicing and are, thus,more susceptible to damage. In addition, the optical fibers at a splicepoint are handled by a technician who splices the fibers and stores thesplices and associated slack in a protective splice closure. In almostall fiber optic communications systems, it is critical that high qualityand high reliability splices be obtained. Fusion and mechanical splicingtechniques and equipment have been developed that permit low loss, highquality, and durable splices to be obtained. However, it may sometimesbe necessary to remake or repair splices to achieve the desired splicequality.

There are many different types of splice closures for protecting opticalfiber splices wherein all of the fibers are spliced to correspondingfibers in an adjacent cable section. Typically, these splice closuresinclude one or more splice organizing trays, on which the individualsplices and the relatively short lengths of associated slack fibers aremounted. For example, the assignee of the present invention manufacturesa conventional splice enclosure and splice organizer under the modeldesignation FOSC 100. Siecor Corporation of Hickory, N.C. makes spliceenclosures under the model designations SC2, and SC4-6. Another spliceenclosure is shown in UK Patent Application No. 2,150,313A assigned toPreformed Line Products of Cleveland, Ohio.

Another common fiber optic communication system application requiringfiber splicing includes a main cable serving several drop cables atspaced apart locations along the route of the main cable. Splices arerequired at these drop points; however, not all of the fibers in themain cable are severed and spliced. Rather, only a relatively smallnumber of fibers are typically spliced to the drop cable. The remainingfibers, or express fibers, are desirably left undisturbed. Accordingly,a large amount of slack is typically associated with these expressfibers. This slack may be in the form of a plurality of buffer tubes,each in turn containing a plurality of fibers.

Fiber optic splice closures have been developed for protecting thesplices between a main cable and a drop cable. Such closures typicallyhave an in-line arrangement of incoming and outgoing cables. Inaddition, such closures typically have a compartment for storing therelatively large amount of slack express fibers. For example, U.S. Pat.No. 4,805,979 to Bossard et al. entitled Fiber Optic Cable SpliceClosure and assigned to 3M, discloses an in-line splice closureincluding two rigid half shells.

Unfortunately, the 3M splice closure is assembled by routing the slackbuffer tubes in a compartment defined by the lower rigid shell, and thesplice organizer trays and cable end attachments are built upon thebottom shell. Thus, initial assembly is somewhat complicated and,moreover, the slack is extremely difficult to reaccess once the closureis assembled as the bottom shell cannot be removed without substantiallydisassembling the entire splice closure.

U.S. Pat. No. 4,679,896 to Krafcik et al. entitled Optical Fiber SpliceOrganizer discloses a splice closure including a bottom slack storagetray positioned within a cylindrical housing. The slack stored in thetray may only be accessed after removing a series of stacked spliceorganizers from a pair of upwardly extending threaded studs. Stated inother words, the access opening for the slack storage tray is covered bythe stacked splice organizers and access to the slack requiresdisturbing the splice trays.

Somewhat similar to the Krafcik et al. splice closure is the closuredescribed in U.S. Pat. No. 4,428,645 to Korbelak et al. entitled CableAccumulator. The splice closure includes a hinged and removable spliceorganizer and underlying compartment or tray for slack cable. The spliceorganizer must be pivoted out of the way to gain access to the slackstorage compartment opening.

Similar to such conventional splice closures, is splice closure modelFOSC 100®D manufactured by Raychem, assignee of the present invention.The FOSC 100®D includes as an option, a slack storage compartment thatmay be mounted underlying a series of pivotally secured spliceorganizing trays. The access opening for the slack storage compartmentis covered by the splice organizing trays; however, the splice trays maybe pivoted upward to gain access to the slack. Thus, the splice traysmust still be repositioned to access the underlying slack.

There are other applications where conventional splice closures havesignificant shortcomings. For example, when a new drop point must beadded to an existing or preinstalled main cable, a so-called "tautsheath" splice is desirable. Unfortunately, conventional splice closure,such as the 3M closure, may be too short to permit sufficient slackfibers to be exposed from the cable. Similarly, for a taut sheath ringsplice, wherein both incoming and outgoing fibers are spliced to a dropcable, a conventional closure does not permit obtaining sufficient slackfor splicing.

Another shortcoming of conventional splice closures is that the use ofsuch closures is expensive for a typical repair of a severed cable,since two splice closures must be used. In other words, in aconventional repair, a patch length of slack cable is spliced to restorethe damaged cable section and two splice closures are used to protecteach of the splices to the patch cable ends.

OBJECTS AND SUMMARY OF THE INVENTION

In view of the foregoing background, it is therefore an object of thepresent invention to provide a splice closure for securing optical fibersplices and slack, while facilitating initial access and reaccess toeither the slack or the splices without disturbing the other.

It is another object of the present invention to provide a spliceclosure and associated method for facilitating splicing of a drop cable,for example, to a fiber optic cable that has already been installed,such as in a taut sheath fiber splice.

It a further object of the present invention to provide a splice closureand associated method for repairing a damaged fiber optic cable.

These and other objects, features, and advantages of the presentinvention are provided by a splice closure including an elongate frameand partition wall means for defining opposing front and rear, or firstand second, opposing access areas for splice organizer means and slackstorage means. In other words, the splice closure according to theinvention permits access to the splices and slack relative independentfrom one another, thereby facilitating initial assembly and reaccesswithin the splice closure.

The wall partition means defines surface portions extendinglongitudinally between opposing ends of the frame. Thus, the spliceorganizing means is on the front or first surface portion so that thesplices are accessible from a first access area, while the slack storagemeans is on the second surface portion of the partition wall means andstores slack optical fibers so that the slack is accessible from thesecond access area. The slack storage means preferably includes one ormore pairs of opposing spaced apart sidewalls depending from the wallpartition means and defining a slack storage access opening forfacilitating access to the slack optical fibers from the second accessarea.

In one embodiment of the splice closure, the splice organizing meanspreferably includes a plurality of splice trays, and mounting means formounting the splice trays in a stack. More particularly, the mountingmeans preferably includes means for pivotally mounting an end of eachsplice tray for pivotal movement between a stored position, generallyparallel with the wall partition means, and a raised position,facilitating access to an underlying splice tray.

Another embodiment of the splice closure according to the presentinvention includes a second plurality of splice trays, and secondmounting means for mounting the splice trays in a second stacklongitudinally adjacent the first stack on the wall partition means. Thesecond mounting means also preferably includes second means forpivotally mounting an end of each splice tray for pivotal movementbetween the stored and raised positions. In other words, this tandemsplice tray embodiment preferably includes an elongate frame, and spliceorganizing means on the frame, and wherein the splice organizing meanspreferably includes a plurality of splice trays and first and secondmounting means for mounting at least one of the splice trays in each ofrespective first and second longitudinally adjacent positions on theelongate frame.

The tandem splice tray embodiment may be useful for a number ofapplications, such as for facilitating the repair of a severed cable. Inaddition, the embodiment may have application in a taut sheath splice,and especially in a taut sheath ring splice, as more fully describedbelow with respect to method aspects of the present invention.

Another feature of the splice closure according to the present inventionis that the wall partition means includes at least one guide openingtherethrough for routing optical fibers between the first and secondaccess areas. Moreover, the guide opening preferably opens outwardly toan edge of the wall partition means to facilitate positioning of opticalfibers through the guide opening without requiring severing of theoptical fibers.

In one embodiment of the invention, the wall partition means includes apair of opposing spaced apart generally rectangular walls lying in acommon plane and extending in a longitudinal direction. The spacebetween the two walls defines a longitudinally extending guide openingfor routing optical fibers between the first and second access areas.

In another embodiment, the wall partition means is provided by agenerally rectangular wall having at least one T-shaped opening therein.The T-shaped opening may be relatively large and located in alongitudinally central portion of the rectangular wall, or a pair ofrelatively small T-shaped openings may be provided adjacent opposing endportions of the rectangular wall.

Another aspect of the present invention is that a longitudinal extensionmember may be connected to an end of the wall partition means to providean extended length for the closure. The extended length may be desirablein certain applications, such as a taut sheath cable splice, forexample, as described more fully below according to a method aspect ofthe invention. In one embodiment, the extensible member may be providedby a rectangular wall or plate connected in end-to-end relation to theelongate frame.

The splice closure according to the invention also preferably includes ahousing surrounding the frame, the splice organizer means, and the slackstorage means. In one embodiment, such as for strict environmentalsealing, the housing may be a tubular metal shell with a heatrecoverable material surrounding the tubular shell. The tubular shellmay be provided by two longitudinally extending sections, each having asemicircular cross-sectional shape. The tubular shell may also havetapered end portions defining a frustoconical shape for sealing the endsof the housing where the relatively smaller diameter cables enter. Tofurther enhance sealing of the housing ends, a pair of elongate bodiesare preferably positioned extending longitudinally outward fromrespective ends of the frame to engage respective ends of the heatrecoverable material housing.

Another aspect of the invention provides a tubular shell including firstand second longitudinally extending sections. Accordingly, an endportion of the first section is slidably positioned within an endportion of the second section. Thus, the length of the housing may bereadily adjusted in the field by the technician to accommodate the framelength and an extension member, as desired. In addition, the heatrecoverable material is available relatively long lengths and may bereadily cut to length.

In another embodiment of the invention, such as for aerial applicationswhere strict environmental sealing is not required, the housingpreferably includes first and second longitudinally extending plasticpanels. The panels are preferably joined together by an integrallymolded lengthwise extending hinge.

The splice closure according to the present invention is preferably usedin an in-line configuration. Accordingly, the splice closure preferablyincludes cable securing means carried by opposing end portions of theframe for securing respective fiber optic cables to the frame in thein-line configuration.

One method aspect of the present invention is for making a taut sheathfiber optic cable splice to one or more optical fibers in a cable of thetype having an outer jacket and plurality of buffer tubes containingoptical fibers. More particularly, the buffer tubes are arranged arounda central supporting member in an oscillating helical lay pattern havinga predetermined period.

The method includes providing a splice closure including an elongateframe and splice organizing means mounted thereon for holding one ormore optical fiber splices, the frame having a predetermined length asleast as great as the period of the oscillating helical lay pattern ofthe cable. The jacket is removed from the predetermined longitudinalportion of the cable corresponding to the period of the oscillatinghelical lay pattern of an underlying predetermined buffer tube tothereby produce slack in the buffer tube. The cable is secured to theframe and the one or more fibers of the predetermined buffer tube arespliced to respective fibers of another fiber optic cable. The splicesare secured within the splice organizer means and the housing is placedsurrounding the splice organizer means and the frame.

For a typical taut sheath splice, the splice closure including theextension member may be used to provide the additional length requiredto obtain sufficient slack. For a taut sheath ring splice, the tandemsplice tray splice closure may be advantageously used.

Another method aspect according to the invention is directed torepairing a severed portion of a fiber optic cable. The method includesthe steps of providing a splice closure including an elongate frame, andsplice organizing means on the frame for securing splices betweenpredetermined optical fibers. The splice organizing means includes aplurality of splice trays and first and second mounting means formounting at least one of the splice trays in each of respective firstand second longitudinally adjacent positions on the elongate frame. Inother words, the tandem splice tray splice closure is provided. Othersteps include: securing respective first and second ends of the fiberoptic cable to respective opposing ends of the elongate frame of thesplice closure, making first and second splices between a patch opticalfiber and respective first and second ends of each severed opticalfiber, and positioning the first and second splices in splice trays atrespective first and second longitudinally adjacent positions on theelongate frame. Accordingly, the tandem longitudinal arrangement of thesplice trays permits obtaining slack for repairing each severed opticalfiber with an intervening patch optical fiber. The splice closure alsopreferably includes a housing surrounding the frame and the two stacksof splice trays.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an embodiment of the spliceclosure according to the invention.

FIG. 2 is a rear perspective view of the embodiment of the spliceclosure as shown in FIG. 1 with the housing removed for clarity.

FIG. 3 is an enlarged plan view of the embodiment of the splice closureas shown in FIG. 1 with the housing removed for clarity.

FIG. 4 is a fragmentary front view of another embodiment of the spliceclosure according to the present invention.

FIG. 5 is a greatly enlarged plan view of a portion of the embodiment ofthe splice closure shown in FIG. 4 with the housing removed for clarity.

FIG. 6 is a cross-sectional view of the housing of the splice closuretaken along lines 6--6 as shown in FIG. 4.

FIG. 7 is a cross-sectional view of the housing of the splice closure asin FIG. 6 shown in an open position to facilitate assembly.

FIG. 8 is a front view of yet another embodiment of the splice closureaccording to the invention with the housing removed and without theoptical fibers or splices being shown for clarity.

FIG. 9 is front view of another embodiment of the splice closureaccording to the invention illustrating a tandem arrangement of splicetrays, and with the housing removed for clarity.

FIG. 10 is a perspective view of another embodiment of a housingaccording to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, applicants provide theseembodiments so that this disclosure will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart. Like numbers are used in alternate embodiments to designate similarelements.

Referring first to FIGS. 1-3, a first embodiment of the splice closure15 according to the invention is explained. The splice closure 15 is forsecuring splices 19 between individual optical fibers 20 extending fromone or more fiber optic buffer tubes 23 of one or more fiber opticcables 22.

The splice closure 15 includes an elongate frame 16 having opposingends. More particularly, in the illustrated embodiment, the frame 16includes wall partition means provided by a pair of spaced apartgenerally rectangular walls 17 lying in a common plane and extending ina longitudinal direction. The wall partition means provided by thespaced apart walls 17 defines opposing first and second surface portionsextending longitudinally between opposing ends of the frame 16. Theseopposing first and second surface portions, in turn, define respectiveopposing first and second, or front and rear, access areas ashighlighted in FIG. 3.

Splice organizing means is positioned on the first or front surfaceportion of the pair of walls 17 for securing splices 19 betweenpredetermined optical fibers 20 so that the splices are accessible fromthe first access area. As shown in the illustrated embodiment, thesplice organizing means includes a plurality of splice trays 25, andmounting means for mounting the splice trays in a stack. The mountingmeans preferably includes means for pivotally mounting an end of eachsplice tray 25 for pivotal movement between a stored position, generallyparallel with the pair of walls 17, and a raised position, facilitatingaccess to an underlying splice tray as also shown best in FIG. 3.

As shown in the illustrated embodiment, the pivotal mounting meansincludes a bracket 26 having a series of openings therein receivinghinge pins 27 for pivotally mounting the splice trays 25 to the frame16. Other pivotal mounting arrangements will be readily appreciated bythose skilled in the art.

The bracket 26 is integrally formed with the pair of walls 17 formingthe wall partition means. Accordingly, the frame 16 includes a secondintegrally formed bracket 28 at an opposite end of the frame so that theframe may be formed from a single sheet of metal.

Slack storage means is provided on the second or rear surface portion ofthe pair of walls 17 for storing slack 30 contained within buffer tubesas shown in the illustrated embodiment. Accordingly, the slack 30 isaccessible from the second access area, and may be initially accessedand reaccessed without unnecessarily disturbing the splice trays 25. Aswould be readily understood by those skilled in the art, the slack 30may be in the form of buffer tubes, individual fibers, or transporttubes, for example.

The slack storage means preferably includes one or more pairs ofopposing spaced apart sidewalls 32a, 32b depending from the pair ofwalls 17 which provide the wall partition means. In the illustratedembodiment, the sidewalls include respective inwardly facing tabs 34a,34b to further secure the slack 30 in place. In addition, the sidewalls32a, 32b have an arcuate shape corresponding to the circularcross-section shape of the housing 40 described in greater detail below.The free ends of the sidewalls 32a, 32b and their respective tabs 34a,34b thus define a slack storage access opening for facilitating accessto the slack optical fibers from the second or rear access area (FIGS. 2and 3).

Referring now more particularly to FIG. 2, the pair of walls 17 whichprovide the wall partition means also define a longitudinally extendingguide opening 37 for routing optical fibers between the first and secondaccess areas. The guide opening 37 also opens outwardly to an end edgeof the wall partition means to facilitate positioning of optical fibersthrough the guide opening without requiring severing of the opticalfibers.

Referring now more particularly to FIG. 1, the splice closure alsopreferably includes a housing 40 surrounding the frame 16, the spliceorganizer means, and the slack storage means. As shown in theillustrated embodiment, the housing 40 includes a tubular shell havingfirst and second halves 41a, 41b and a heat recoverable material sheet42 surrounding the tubular shell. As would be readily understood bythose skilled in the art, the housing 40 is preferably of theconventional type used in splicing of copper cables commonly used in thetelephone industry.

The shell halves 41a, 41b each preferably have a semicircularcross-sectional shape, and a plurality of tapered end portions fordefining a frustoconical shape for the housing ends when the heatrecoverable material sheet 42 is heated and draws down upon the shell.In addition, each shell half 41a, 41b also preferably includes a seriesof longitudinally spaced apart tabs 43 offset on opposing shell edges tothereby form a hingelike joint.

The heat recoverable material sheet 42 preferably includes an adhesiveflap portion 45 for sealing the longitudinal seam between the opposingbeaded edges 47 of the sheet. In addition, a clip 46 is preferably usedto secure the opposing beaded edges 47 of the heat recoverable materialsheet 42.

To further assist in sealing the end portions of the housing 40, thesplice closure preferably also includes a pair of elongate tubularbodies 48 extending longitudinally outward from respective ends of theframe 16. The tubular bodies are secured to respective brackets 26, 28at each end of the frame 16. The elongate tubular bodies 48 increase theminimum diameter to which the heat recoverable material of the housing40 must shrink to seal the ends of the housing to the entering cables22.

The elongate tubular bodies 48 also cooperate with respective fasteners,such as tie wraps 49, to provide means for securing the fiber opticcables 22 to the frame 16 in an in-line configuration. To further reducethe likelihood of water migration into the interior of the spliceclosure 15, the ends of the cables 22 may be sealed by a water blockingcompound and heat shrink tubular cover 50 as would be readily understoodby those skilled in the art.

Referring now to FIGS. 4-7 a second embodiment of the splice closure 60according to the invention is explained. This embodiment of the spliceclosure 60 is particularly well suited for an aerial installation asshown, wherein the splice closure is supported from an overheadmessenger strand 61. To facilitate understanding of this embodiment,like numbers are used where possible for like elements discussed abovewith respect to the embodiment of the splice closure as shown in FIGS.1-3.

The splice closure 60 includes an elongate frame 62 on which spliceorganizing means pivotally secures a plurality of splice trays 25. Thesplice trays 25 hold splices 19 between predetermined optical fibers 20from predetermined fiber optic cables 22. The splice closure 60 alsoincludes wall partition means provided by a generally rectangular wall63. The splice organizer means is on a first or front surface portion ofthe generally rectangular wall 63.

Slack storage means is on the second or back surface of the generallyrectangular wall 63 so that the slack 30 is accessible from the secondor rear access area (FIG. 5). The slack storage means is provided by oneor more pairs of opposing sidewalls, only one sidewall 34b being shownin the illustrated embodiment for clarity. The sidewalls define a slackaccess opening for the splice closure 60.

A relatively large T-shaped guide opening 67 (FIG. 4) is provided in acentral or medial portion of the generally rectangular wall 62 so thatslack 30 may be readily positioned within the slack storage means androuted between the first and second access areas of the splice closure60. The T-shaped guide opening 67 preferably opens outwardly to a bottomedge of the generally rectangular wall 63 as shown in the illustratedembodiment. Accordingly, the express buffer tubes 23 not being accessedmay be readily positioned into the slack storage means without requiringcutting of the buffer tubes.

The frame 62 of the splice closure 60 is suspended from the messenger 61by a pair of metal L-shaped members 65. An insulator, not shown, may bepositioned between each of the L-shaped members 65 and the frame 62 toelectrically isolate the frame. In addition, proper alignment of thefiber optic cables 22 entering the splice closure 60 is maintained bystacked spacers blocks 66 as would be readily understood by thoseskilled in the art.

As shown in the illustrated embodiment, the splice closure 60 is suitedfor splicing cables 22 in an in-line configuration. Accordingly, thesplice closure 60 includes means for securing the cables 22 in anin-line configuration. More particularly, the generally rectangular wall63 includes openings 68 adjacent each end defining stubs 69 for securingends of the cable 22 thereto with a fastener, such as a band clamp 70.

The housing 75 for the splice closure 60 as illustrated includes firstand second longitudinally extending corrugated plastic panels 76, and anintegrally molded longitudinally extending hinge portion 78interconnecting the plastic panels. The housing 75 includes generallyrectangular end openings 79 which are secured around correspondingrectangularly shaped end caps 80 through which the cables 22 enter thesplice closure. As shown in FIGS. 6 and 7, the plastic panels 76 arejoined together at their bottom edges by respective projections 81 andcorresponding openings 82.

Referring now to FIG. 8, another aspect of the present invention isexplained. In certain applications, access to a relatively long lengthof optical fibers 20 contained within the fiber optic cable 22 may berequired. For example, it may be desirable to add a drop cable to a maincable that is already installed, that is, to make a taut sheath splice.Accordingly, the embodiment of the splice closure 90 as illustrated maythus be used to mount and protect the splices and the exposed relativelylong portion of the cable. To accommodate such a requirement, alongitudinal extension member 95 may be connected to an end of the frame91. In the illustrated embodiment, the frame 91 includes a generallyrectangular wall 92.

The extension member 95 and the generally rectangular wall 92 may haveoverlapping ends as illustrated and fastening means for securing theends together with an adjustable degree of overlap to provide apredetermined length for the splice closure 90. As shown in theillustrated embodiment, the fastening means includes a pair of slottedopenings 97 in each extension member 95 and the generally rectangularwall 92, and a pair of bolts 98 extending through the respectiveopenings. As would be readily understood by those skilled in the art,other shapes of longitudinal extension member may also be provided, andother attachment arrangements for the extension member are contemplatedby the invention.

FIG. 8 also illustrates another feature of the invention, that is, apair of relatively small T-shaped openings 99 provided in the generallyrectangular wall 92 for facilitating routing of fibers between the frontand rear access areas of the splice closure 90. As illustrated, theT-shaped openings 99 open outwardly to an upper edge of the generallyrectangular wall 92.

Referring now to FIG. 9, another embodiment of a splice closure 110according to the invention is illustrated. This embodiment of the spliceclosure 110 includes a marriage of the components of two splice closures15 as illustrated in FIGS. 1-3. Thus, where possible, like referencenumbers are used in FIG. 9 and the following description for ease ofunderstanding.

More particularly, as shown in the central portion of FIG. 9, therespective frames 16 of two splice closures are joined in end-to-endrelation by positioning fasteners, not shown, through each protrudingtab 111 and corresponding opening, not shown, in the flames. As would bereadily understood by those skilled in the art, other securingarrangements may also be used.

The illustrated embodiment of the splice closure 110 includes first andsecond mounting means for mounting the plurality of splice trays 25 inrespective first and second longitudinally adjacent stacks on the joinedtogether frames 16. As discussed above with respect to FIGS. 1-3, eachof the first and second mounting means preferably include means forpivotally mounting an end of each splice tray 25 for pivotal movementbetween a stored position, generally parallel with the frame, and araised position, facilitating access to an underlying splice tray.

The entry of optical fibers 20 into each splice tray 25 in respectivestacks is immediately adjacent respective ends of the splice closure110. Accordingly, more efficient usage of the slack is achieved. Theother attendant features and benefits including splice access from thefront access and area, and slack access from the rear access area arealso present in the embodiment illustrated in FIG. 9.

The splice closure 110 with the tandem sets of splice trays 25 may havea wide number of applications. In particular, the splice closure 110 maybe readily used to repair a severed cable while requiring the use ofonly one splice closure 110 rather than two as in the prior art. Thismethod aspect of the invention is discussed further below. Anotherapplication for the splice closure is a taut sheath ring splice. Yetanother application for the splice closure 110 may include achieving ahigher capacity for splices within the closure. These and yet otherapplications for the splice closure 110 will be readily appreciated bythose skilled in the art.

Another aspect of the embodiments of the splice closures 90 and 110 asshown in FIGS. 8 and 9, respectively, is that each relatively longassembly may be readily surrounded by a single housing of sufficientlength. A housing 75 of the type as shown in FIGS. 4, 6 and 7 may beused, such as for an aerial application where strict environmentalsealing is not required. Alternatively, a heat recoverable housing 40 ofthe type shown in FIG. 1 may be used for the embodiments illustrated inFIGS. 8 and 9. In addition, another variation of an extensible heatrecoverable housing 120 is shown in FIG. 10.

As shown in FIG. 10, the housing 120 includes first and secondlongitudinally extending sections 121, wherein an end portion of thefirst section is slidably positioned with an end portion of the secondsection. Thus, the length of the housing 120 may be selected byadjusting the amount of overlap of the ends of the longitudinallyextending sections 121, and cutting the heat recoverable material sheet42 and the securing clip 46 to a corresponding length. Although notshown for clarity, each of the shell sections 121 may, in turn, includea pair of longitudinal sections as shown in FIG. 1.

One method aspect of the present invention is for making a taut sheathsplice to one or more optical fibers in a cable of the type having anouter jacket and plurality of buffer tubes containing optical fibers.More particularly, as would be readily understood by those skilled inthe art, the buffer tubes are arranged around a central supportingmember in an oscillating helical lay pattern having a predeterminedperiod. In other words, the helical lay pattern reverses at regularintervals along the cable.

The method includes providing a splice closure including an elongateframe and splice organizing means mounted thereon for holding one ormore optical fiber splices, the frame having a predetermined length asleast as great as the period of the oscillating helical lay pattern ofthe cable. The jacket is removed from a predetermined longitudinalportion of the cable corresponding to the period of the oscillatinghelical lay pattern of an underlying predetermined buffer tube tothereby produce slack in the predetermined buffer tube. Thepredetermined longitudinal portion of the cable is secured to the frame.Splicing of one or more of the fibers of the predetermined buffer tubeto respective one or more fibers of another fiber optic cable isperformed, and the splices are secured within the splice organizermeans.

The taut sheath splice is also preferably protected by securing ahousing of the splice closure around the frame and the splice organizermeans. In addition, the step of providing the elongate frame ofpredetermined length preferably includes the step of adding an extensionmember to a first longitudinally extending portion of the frame on whichthe splice organizer means is mounted as described above. Alternatively,the step of providing the splice closure may include providing thetandem splice tray embodiment of the splice closure as also describedabove.

Another method aspect according to the invention is directed torepairing a severed portion of a fiber optic cable. The method includesthe steps of providing a splice closure including an elongate frame, andsplice organizing means on the frame for securing splices betweenpredetermined optical fibers, the splice organizing means including aplurality of splice trays and first and second mounting means formounting at least one of the splice trays in each of respective firstand second longitudinally adjacent positions on the elongate frame. Inother words, the tandem splice tray splice closure is provided.

The other steps of the repair method include securing respective firstand second ends of the fiber optic cable to respective opposing ends ofthe elongate frame of the splice closure, making first and secondsplices between a patch optical fiber and respective first and secondends of each severed optical fiber, and positioning the first and secondsplices in splice trays at respective first and second longitudinallyadjacent positions on the elongate frame. Accordingly, the tandemlongitudinal arrangement of the splice trays permits obtaining slack forrepairing each severed optical fiber with an intervening patch opticalfiber.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is to be understood that the invention is not to belimited to the specific embodiments disclosed, and that modificationsand embodiments are intended to be included within the scope of theappended claims.

That which is claimed is:
 1. A fiber optic splice closure for one ormore fiber optic cables of the type having one or more optical fibers,said splice closure comprising:an elongate frame having opposing ends,said frame including partition wall means for defining opposing firstand second surface portions extending longitudinally between opposingends of said frame, said opposing first and second surface portionsdefining respective opposing first and second access areas; spliceorganizing means on the first surface portion of said partition wallmeans for securing splices between predetermined optical fibers so thatthe splices are accessible and reaccessible from the first access areawithout disturbing the second access area; and slack storage means onthe second surface portion of said partition wall means for storingslack optical fibers so that the slack optical fibers are accessible andreaccessible from the second access area without disturbing the firstaccess area.
 2. A splice closure according to claim 1 wherein said slackstorage means comprises a pair of opposing spaced apart sidewallsdepending from said wall partition means and defining a slack storageaccess opening for facilitating access to the slack optical fibers fromthe second access area.
 3. A splice closure according to claim 1 whereinsaid splice organizing means comprises a plurality of splice trays, andmounting means for mounting said splice trays in a stack, and whereinsaid mounting means includes means for pivotally mounting an end of eachsplice tray for pivotal movement between a stored position generallyparallel with said wall partition means and a raised positionfacilitating access to an underlying splice tray.
 4. A splice closureaccording to claim 3 further comprising a second plurality of splicetrays, and second mounting means for mounting said splice trays in asecond stack longitudinally adjacent the first stack on said wallpartition means, and wherein said second mounting means includes secondmeans for pivotally mounting an end of each splice tray for pivotalmovement between a stored position generally parallel with said wallpartition means and a raised position facilitating access to anunderlying splice tray.
 5. A splice closure according to claim 1 whereinsaid wall partition means includes at least one guide openingtherethrough for routing optical fibers between said first and secondaccess areas.
 6. A splice closure according to claim 5 wherein said atleast one guide opening is open outwardly to an edge of said wallpartition means to facilitate positioning of optical fibers through saidat least one guide opening without requiring severing of the opticalfibers.
 7. A splice closure according to claim 1 wherein said wallpartition means comprises a pair of opposing spaced apart generallyrectangular walls lying in a common plane and extending in alongitudinal direction thereby defining a longitudinally extending guideopening for routing optical fibers between said first and second accessareas.
 8. A splice closure according to claim 1 wherein said wallpartition means comprises a generally rectangular wall having at leastone T-shaped opening therein and defining at least one guide opening forrouting optical fibers between said first and second access areas.
 9. Asplice closure according to claim 1 further comprising a longitudinalextension member connected to an end of said wall partition means.
 10. Asplice closure according to claim 1 further comprising a housingsurrounding said frame, said splice organizer means, and said slackstorage means.
 11. A splice closure according to claim 10 wherein saidhousing comprises a tubular shell and a heat recoverable materialsurrounding said tubular shell.
 12. A splice closure according to claim11 wherein said tubular shell comprises first and second longitudinallyextending sections, and wherein an end portion of the first section isslidably positioned within an end portion of the second section.
 13. Asplice closure according to claim 11 further comprising a pair ofelongate bodies extending longitudinally outward from respective ends ofsaid frame and engaging respective ends of said heat recoverable housingto enhance sealing of same.
 14. A splice closure according to claim 10wherein said housing comprises first and second longitudinally extendingplastic panels, and an integrally molded lengthwise extending hingeportion interconnecting said first and second plastic panels.
 15. Asplice closure according to claim 1 further comprising cable securingmeans carried by opposing end portions of said frame for securingrespective fiber optic cables to said frame in an in-line configuration.16. A fiber optic splice closure for one or more fiber optic cables ofthe type having one or more optical fibers, said splice closurecomprising:an elongate frame having opposing ends, said frame includingpartition wall means for defining opposing first and second surfaceportions extending longitudinally between opposing ends of said frame,said opposing first and second surface portions defining respectiveopposing first and second access areas; splice organizing means on thefirst surface portion of said partition wall means for securing splicesbetween predetermined optical fibers so that the splices are accessibleand reaccessible from the first access area, said splice organizingmeans comprising a plurality of splice trays and mounting means formounting said splice trays in a stack, said mounting means includingmeans for pivotally mounting an end of each splice tray for pivotalmovement between a stored position generally parallel with said wallpartition means and a raised position facilitating access to anunderlying splice tray; and slack storage means on the second surfaceportion of said partition wall means for storing slack optical fibers sothat the slack optical fibers are accessible and reaccessible from thesecond access area, said slack storage means comprising a pair ofopposing spaced apart sidewalls depending from said wall partition meansand defining a slack storage access opening for facilitating access tothe slack optical fibers from the second access area.
 17. A spliceclosure according to claim 16 wherein said splice organizing meansfurther comprises a second plurality of splice trays, and secondmounting means for mounting said splice trays in a second stacklongitudinally adjacent the first stack on said wall partition means,and wherein said second mounting means includes second means forpivotally mounting an end of each splice tray for pivotal movementbetween a stored position generally parallel with said wall partitionmeans and a raised position facilitating access to an underlying splicetray.
 18. A splice closure according to claim 16 wherein said wallpartition means includes at least one guide opening therethrough forrouting optical fibers between said first and second access areas.
 19. Asplice closure according to claim 18 wherein said at least one guideopening is open outwardly to an edge of said wall partition means tofacilitate positioning of optical fibers through said at least one guideopening without requiring severing of the optical fibers.
 20. A spliceclosure according to claim 16 wherein said wall partition meanscomprises a pair of opposing spaced apart generally rectangular wallsextending in a common plane and in a longitudinal direction therebydefining a longitudinally extending guide opening for routing opticalfibers between said first and second access areas.
 21. A splice closureaccording to claim 16 wherein said wall partition means comprises agenerally rectangular wall having at least one T-shaped opening thereinand defining at least one guide opening for routing optical fibersbetween said first and second access areas.
 22. A splice closureaccording to claim 16 further comprising a longitudinal extension memberconnected to an end of said wall partition means.
 23. A splice closureaccording to claim 16 further comprising a housing surrounding saidframe, said splice organizer means, and said slack storage means.
 24. Asplice closure according to claim 23 wherein said housing comprises atubular shell and a heat recoverable material surrounding said tubularshell.
 25. A splice closure according to claim 24 wherein said tubularshell comprises first and second longitudinally extending sections, andwherein an end portion of the first section is slidably positionedwithin an end portion of the second section.
 26. A splice closureaccording to claim 24 further comprising a pair of elongate bodiesextending longitudinally outward from respective ends of said frame andengaging respective ends of said heat recoverable housing to enhancesealing of same.
 27. A splice closure according to claim 23 wherein saidhousing comprises first and second longitudinally extending plasticpanels, and an integrally molded lengthwise extending hinge portioninterconnecting said first and second plastic panels.
 28. A spliceclosure according to claim 16 further comprising cable securing meanscarried by opposing end portions of said frame for securing respectivefiber optic cables to said frame in an in-line configuration.
 29. Afiber optic splice closure for one or more fiber optic cables of thetype having one or more optical fibers, said splice closurecomprising:an elongate frame; splice organizing means on said frame forsecuring splices between predetermined optical fibers, said spliceorganizing means comprising a plurality of splice trays and first andsecond mounting means for mounting said plurality of splice trays inrespective first and second longitudinally adjacent stacks on saidframe, each of said first and second mounting means including means forpivotally mounting an end of each splice tray for pivotal movementbetween a stored position generally parallel with said frame and araised position facilitating access to an underlying splice tray; saidelongate frame including partition wall means for defining opposingfirst and second surface portions extending longitudinally betweenopposing ends of said frame, wherein said opposing first and secondsurface portions define respective opposing first and secondreaccessible access areas, and wherein said splice organizing means ison the first surface portion of said wall partition means; and slackstorage means on the second surface portion of said wall partition meansfor storing slack optical fibers.
 30. A splice closure according toclaim 29 wherein said slack storage means comprises a pair of opposingspaced apart sidewalls depending from said partition wall means anddefining a slack storage access opening for facilitating access to theslack optical fibers from the second access area.
 31. A splice closureaccording to claim 29 further comprising a housing surrounding saidframe, and said splice organizer means.
 32. A splice closure accordingto claim 31 wherein said housing comprises a tubular shell and a heatrecoverable material surrounding said tubular shell.
 33. A spliceclosure according to claim 32 wherein said tubular shell comprises firstand second longitudinally extending sections, and wherein an end portionof the first section is slidably positioned within an end portion of thesecond section.
 34. A splice closure according to claim 32 furthercomprising a pair of elongate bodies extending longitudinally outwardfrom respective ends of said frame and engaging respective ends of saidheat recoverable housing to enhance sealing of same.
 35. A spliceclosure according to claim 31 wherein said housing comprises first andsecond longitudinally extending plastic panels, and an integrally moldedlengthwise extending hinge portion interconnecting said first and secondplastic panels.
 36. A splice closure according to claim 29 furthercomprising cable securing means carried by opposing end portions of saidframe for securing respective fiber optic cables to said frame in anin-line configuration.
 37. A fiber optic splice closure for one or morefiber optic cables of the type having one or more optical fibers, saidsplice closure comprising:an elongate frame; splice organizing means onsaid frame for securing splices between predetermined optical fibers,said splice organizing means comprising a plurality of splice trays andfirst and second mounting means for mounting at least one of said splicetrays in each of respective first and second longitudinally adjacentpositions on said elongate frame; said elongate frame includingpartition wall means for defining opposing first and second surfaceportions extending longitudinally between opposing ends of said frame,wherein said opposing first and second surface portions definerespective opposing first and second reaccessible access areas, andwherein said splice organizing means is on the first surface portion ofsaid wall partition means; and slack storage means on the second surfaceportion of said wall partition means for storing slack optical fibers.38. A splice closure according to claim 37 wherein said slack storagemeans comprises a pair of opposing spaced apart sidewalls depending fromsaid partition wall means and defining a slack storage access openingfor facilitating access to the slack optical fibers from the secondaccess area.
 39. A splice closure according to claim 37 furthercomprising a housing surrounding said frame, and said splice organizermeans.
 40. A splice closure according to claim 39 wherein said housingcomprises a tubular shell and a heat recoverable material surroundingsaid tubular shell.
 41. A splice closure according to claim 40 whereinsaid tubular shell comprises first and second longitudinally extendingsections, and wherein an end portion of the first section is slidablypositioned within an end portion of the second section.
 42. A spliceclosure according to claim 40 further comprising a pair of elongatebodies extending longitudinally outward from respective ends of saidframe and engaging respective ends of said heat recoverable housing toenhance sealing of same.
 43. A splice closure according to claim 39wherein said housing comprises first and second longitudinally extendingplastic panels, and an integrally molded lengthwise extending hingeportion interconnecting said first and second plastic panels.
 44. Asplice closure according to claim 37 further comprising cable securingmeans carried by opposing end portions of said frame for securingrespective fiber optic cables to said frame in an in-line configuration.45. A fiber optic splice closure for fiber optic cables of the typehaving one or more optical fibers, said splice closure comprising:anelongate frame; splice organizer means on said frame for securingoptical fiber splices between respective fiber optic cables; alongitudinal extension member connected to an end of said frame; cablesecuring means carried by opposing end portions of said frame and saidextension member for securing a fiber optic cable in an in-lineconfiguration; and a housing extending longitudinally along said frameand said extension member, said housing surrounding said frame, saidextension member and said splice organizer means.
 46. A splice closureaccording to claim 45 wherein said housing comprises a tubular shell anda heat recoverable material surrounding said tubular shell.
 47. A spliceclosure according to claim 46 wherein said tubular shell comprises firstand second longitudinally extending sections, and wherein an end portionof the first section is slidably positioned within an end portion of thesecond section.
 48. A splice closure according to claim 46 furthercomprising a pair of elongate bodies extending longitudinally outwardfrom respective ends of said frame and said extension member andengaging respective ends of said heat recoverable housing to enhancesealing of same.
 49. A splice closure according to claim 45 wherein saidhousing comprises first and second longitudinally extending plasticpanels, and an integrally molded lengthwise extending hinge portioninterconnecting said first and second plastic panels.
 50. A spliceclosure according to claim 45 wherein said elongate frame includespartition wall means for defining opposing first and second surfaceportions extending longitudinally between opposing ends of said frame,wherein said opposing first and second surface portions definerespective opposing first and second access areas, and wherein saidsplice organizing means is on the first surface portion of said wallpartition means.
 51. A splice closure according to claim 50 wherein saidsplice organizing means comprises a plurality of splice trays andmounting means for mounting said splice trays in a stack on the firstsurface portion of said partition wall means, and wherein said mountingmeans includes means for pivotally mounting an end of each splice trayfor pivotal movement between a stored position generally parallel withsaid wall partition means and a raised position facilitating access toan underlying splice tray.
 52. A splice closure according to claim 50further comprising slack storage means on the second surface portion ofsaid wall partition means for storing slack optical fibers, and whereinsaid slack storage means comprises a pair of opposing spaced apartsidewalls depending from said partition wall means and defining a slackstorage access opening for facilitating access to the slack opticalfibers from the second access area.